Alan Burlison created HADOOP-12012:
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Summary: Investigate JNI for improving byte array comparison
performance
Key: HADOOP-12012
URL: https://issues.apache.org/jira/browse/HADOOP-12012
Project: Hadoop Common
Issue Type: Sub-task
Components: benchmarks, io, performance
Affects Versions: 2.7.0
Environment: All
Reporter: Alan Burlison
Assignee: Alan Burlison
Priority: Minor
HADOOP-7761 added functionality to compare byte arrays by treating them as
arrays of 64-bit longs for performance. However HADOOP-11466 reverted this
change for the SPARC architecture as it causes misaligned traps which causes
performance to be worse rather than better.
Most platforms have a highly-optimised memcmp() libc function that uses
processor-specific functionality to perform byte array comparison as quickly as
is possible for the platform.
We have done some preliminary benchmarking on Solaris that suggests that, for
reasonably-sized byte arrays, JNI code using memcmp() outperforms both of the
current Java byte-size and long-size implementations on both SPARC and x86 . We
are confirming the results and will repeat the same benchmark on Linux and
report the results here for discussion.
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